> On Dec 20, 2015, at 3:51 PM, Daniel Dunbar <daniel_dun...@apple.com> wrote: > >> >> On Dec 17, 2015, at 1:40 PM, Tom Sheffler via swift-users >> <swift-users@swift.org <mailto:swift-users@swift.org>> wrote: >> >> I’m learning about Swift on Linux and using modules to wrap C libraries. >> One of the things I wanted to do was use libdispatch with blocks from Swift. >> I thought it would be easy to use a module to wrap <dispatch/dispatch.h>. >> >> I made a module called “CDispatch” with a module.modulemap like this >> >> ======= >> module CDispatch [system] { >> header "/usr/include/dispatch/dispatch.h" >> export * >> link "dispatch" >> } >> ======== >> >> Then I created a little demo project called gcd4 whose Source/main.swift >> prints some things and then uses a dispatch queue and a block to print a >> message after 2 seconds delay. >> >> ========= >> CDispatch.dispatch_after(time, queue, { >> print("Delayed!") >> }) >> ======== >> >> The entire project is checked in at https://github.com/sheffler/gcd4 >> <https://github.com/sheffler/gcd4> >> and the CDispatch module is checked in at >> https://github.com/sheffler/CDispatch <https://github.com/sheffler/CDispatch> >> >> If I try to “swift build” the project, it almost works but reports that >> dispatch_after is not found. It seems that this function is not defined if >> the “blocks" feature is not provided at compilation time. >> >> ======== >> Compiling Swift Module 'gcd4' (1 sources) >> /home/sheffler/swift/gcd4/Sources/main.swift:42:1: error: module 'CDispatch' >> has no member named 'dispatch_after' >> CDispatch.dispatch_after(time, queue, { >> ^~~~~~~~~ ~~~~~~~~~~~~~~ >> <unknown>:0: error: build had 1 command failures >> swift-build: exit(1): >> ["/home/sheffler/src/swift-2.2-SNAPSHOT-2015-12-01-b-ubuntu14.04/usr/bin/swift-build-tool", >> "-f", "/home/sheffler/swift/gcd4/.build/debug/gcd4.o/llbuild.yaml”] >> ======== >> >> I got the demo program to work by first using “swift build” to retrieve the >> CDispatch module, and then manually running the compiler like this (and >> including the “-Xcc -fblocks” arguments) >> >> swiftc -v -o gcd4 Sources/main.swift -I .build/debug -j8 -Onone -g -Xcc >> -fblocks -Xcc -F-module-map=Packages/CDispatch-1.0.0/module.modulemap -I >> Packages/CDispatch-1.0.0 -I /usr/local/include >> >> This is all pretty neat! I’ve got blocks, dispatch queues and ARC on >> Ubuntu. I have one question and one remark. >> >> - Am i missing something about how to create the CDispatch module? Why >> can’t “swift build” build this? > > This is mostly an oversight, the libdispatch port has been coming up and you > are perhaps the first person to try to integrate all of these things.
It’s not normal, i know. I’m looking forward to using blocks/dispatch on Linux for a media project. > > I'm not sure yet exactly how we should resolve this, it might be the case > that swiftc should just default to enabling blocks support in the Clang > importer. In any case, can you open a specific bug in JIRA for this issue? I’ll add the issue. > >> - Creating Git repositories for simple modules that wrap a single library >> and include a header file or two seems like too much. I would love to have >> been able to create a sub-directory in my project with a modulemap that >> includes <dispatch/dispatch.h> and links libdispatch.so > > There will be an easier avenue to getting this working once we have some > amount of C support in the package manager. > > Even then, one pro of encouraging the separate definition of module map > packages is so that they can be used by other people. It is cumbersome until > we have a the ecosystem of those packages (and easy ways for people to find > them), but it would be worse if they never ever ended up being shared. I think the package manager direction for Swift is great actually. I just took the opportunity to share some of my early experiences whil I had the chance. > > - Daniel > >> >> Thanks >> Tom >> >> P.S. - I tried to make this easy to check out and compile >> >> >> >> _______________________________________________ >> swift-users mailing list >> swift-users@swift.org <mailto:swift-users@swift.org> >> https://lists.swift.org/mailman/listinfo/swift-users >> <https://lists.swift.org/mailman/listinfo/swift-users>
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